highcharts: titles can be null
highcharts: titles can be null

From their documentation:

https://api.highcharts.com/highcharts/title.text
https://api.highcharts.com/highcharts/yAxis.title.text

dsebastien/DefinitelyTyped,markogresak/DefinitelyTyped,alexdresko/DefinitelyTyped,AgentME/DefinitelyTyped,georgemarshall/DefinitelyTyped,arusakov/DefinitelyTyped,AgentME/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,benliddicott/DefinitelyTyped,chrootsu/DefinitelyTyped,georgemarshall/DefinitelyTyped,aciccarello/DefinitelyTyped,AgentME/DefinitelyTyped,borisyankov/DefinitelyTyped,zuzusik/DefinitelyTyped,magny/DefinitelyTyped,zuzusik/DefinitelyTyped,mcliment/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,aciccarello/DefinitelyTyped,laurentiustamate94/DefinitelyTyped,alexdresko/DefinitelyTyped,arusakov/DefinitelyTyped,georgemarshall/DefinitelyTyped,aciccarello/DefinitelyTyped,rolandzwaga/DefinitelyTyped,dsebastien/DefinitelyTyped,zuzusik/DefinitelyTyped,AgentME/DefinitelyTyped,arusakov/DefinitelyTyped,one-pieces/DefinitelyTyped,AbraaoAlves/DefinitelyTyped,rolandzwaga/DefinitelyTyped,chrootsu/DefinitelyTyped,magny/DefinitelyTyped